Oxidation behaviors of Co-Al-W-0.1B superalloys in a long-term isothermal exposure at 900 °C

Co-Al-W-0.1B superalloys have been isothermally oxidized at 900 °C for 1000, 5000 and 10000 h in order to investigate their oxidation behaviors. The oxide layers and morphologies were characterized by X-ray diffraction and scanning electron microscopy combined with energy-dispersive spectroscopy. After 1000 h exposure, a Co₃W/γ zone, an Al₂O₃ layer, a mixture of Co, Al, W oxides layer and a CoO layer are established on the substrate alloys. After extended oxidation, a discontinuous Al₂O₃ layer in Co-9Al-8W-0.1B and Co-9Al-9W-0.1B alloys leads to an additional mixed oxide layer on the substrate instead of the Co₃W/γ zone. The oxide layers that form on the Co-9Al-8W-0.1B and Co-9Al-9W-0.1B alloys are much thicker than those on the Co-9Al-11W-0.1B alloy, and continuously thicken during oxidation. The higher content of W is beneficial to improving the oxidation resistance as it facilitates a faster formation of Co₃W as well as Al₂O₃.     

Influence of cryogenic thermal cycling treatment on the thermophysical properties of carbon/carbon composites between room temperature and 1900 °C

Influence of cryogenic thermal cycling treatment (from ?120 °C to 120 °C at 1.3 × 10^?3 Pa) on the thermophysical properties including thermal conductivity (TC), thermal diffusivity (TD), specific heat (SH) and coefficient of thermal expansion (CTE) ranging from room temperature to 1900 °C of carbon/carbon (C/C) composites in x-y and z directions were studied. Test results showed that fiber/matrix interfacial debonding, fiber pull-out and microcracks occurred after the cryogenic thermal treatment and they increased significantly with the cycle number increasing, while cycled more than 30 times, the space of microdefects reduced obviously due to the accumulation of cyclic thermal stress. TC, TD, SH and CTE of the cryogenic thermal cycling treated C/C composites were first decreased and then increased in both directions (x-y and z directions) with the increase of thermal cycles. A model regarding the heat conduction in cryogenic thermal cycling treated C/C composites was proposed.     

Microstructures and tensile properties of laser cladded AerMet100 steel coating on 300 M steel

A layer of AerMet100 steel was coated on the surface of forged 300 M steel using laser cladding technique. The chemical compositions, microstructures, hardness and tensile properties of this AerMet100/300 M material were systematically investigated. Results show that the composition of the AerMet100 clad layer is macroscopically homogeneous, and a compositional transition zone with width of 150 μm is observed between the clad layer and heat affected zone. Microstructures in transition zone transform from the fine needle-like bainite in 300 M steel to the lath tempered martensite in AerMet100 clad layer. Microstructures in heat affected zone also gradually change from the thick plate bainite and blocky retained austenite (unstable heat affected zone) to fine needle-like bainite and film-like austenite (stable heat affected zone) due to different thermal cycle processes. Thick plate bainite together with blocky retained austenite in unstable heat affected zone reduce the strength and ductility of AerMet100/300 M material. However, the tensile specimens, consisting of clad layer and stable heat affected zone, show slightly inferior mechanical properties to 300 M steel. Ductile fracture exists in AerMet100 clad layer while quasi-cleavage fracture occurs in the stable heat affected zone.     

Mechanical properties and deformation mechanisms of Ti-3Al-5Mo-4.5 V alloy with varied β phase stability

Evolution of deformation mechanisms and mechanical properties of Ti-3Al-5Mo-4.5 V alloy with different β phase stability have been systematically investigated. β phase stability alteration is achieved through quenching temperature variation from dual α + β field (700 °C) to single β field (880 °C). Tensile tests at ambient temperature show that apparent yield strength of the alloy experiences an abrupt decrease followed by a significant increase from 700 °C to 880 °C. Work hardening behavior is characterized by transition from the initial two-regime feature to the three-stage outlook. Concurrently, the maximum working hardening rate drops from 14000 MPa to 3000 MPa, which is concurrent with the shrinking volume fraction of primary α phase. Detailed discussion about the relationship between deformation mechanisms and β phase stability has been outlined.     

Constitutive equation and model validation for a 31 vol.% B4Cp/6061Al composite during hot compression

An accurate constitutive equation is essential to understanding the flow behavior of B₄C/Al composites during the hot deformation. However, the constitutive equations developed previously in literature are generally for low strain rate deformation. In the present work, we modified the general constitutive equation and take the high strain rate correction into account. The constitutive equation for a 31 vol.% B₄Cp/6061Al composite was constructed based on the flow stresses measured during isothermal hot compression at temperatures ranging from 375 to 525 °C and strain rates from 0.01 to 10 s^?1. The experimental flow stresses were corrected by considering temperature-dependent Arrhenius factor. The modified equation was then verified by using DEFORM-3D finite element analysis to simulate the experimental hot compression process. The results show that the modified equation successfully predicts flow stress, load–displacement, and the temperature rise. This helps to optimize the hot deformation process, and to obtain desirable properties, such as reduced porosity and homogenous particle distribution in B₄C/Al composites.     

路边臭豆腐——乱!乱!乱!

最近一段时间,福州市大街小巷油炸臭豆腐的摊点越来越多,而且多为出店移动经营或者是占道经营,王庄社区以及仓山的一些街道甚至成了"臭豆腐一条街"。最近,不少市民投诉反映,对于好食者来     

2010 并购! 并购!

事件:竞争力、市场垄断、资源整合贯穿了检测认证行业2010年的新闻主题——并购。2010年6月17日,UL成功收购为全球技术市场提供领先的测试、审批和咨询服务的RFI全球服务有限公司,意在提升其无线蜂窝通信及支付系统的全球服务。2010年4月20日,T(U|¨)V南德意志集团(T(U|¨)V S(U|¨)D)宣布并购全球风险顾问公司(GRC),成为全球独立资产风险控制评估领域的领先者。并购GRC之后,T(U|¨)V南德意志集团将继续在美洲及全球进行业务扩张,为保险、风险管理工程和咨询领域提供增值服务。2010年初,UL美国收购了为照明产业提供对灯具及光源产品性能测试的独立测试实验室LTL,此     

1999,齐加油!--来自国家局计量司的声音

刚刚过去的1998年，在社会各界特别是计量同仁的共同努力下，计量工作取得了新的进步，计量事业又得到新的发展。在此辞旧迎新之际，我们向全国计量战线的广大干部职工表示衷心的感谢和亲切的问候！1999年，我们计量司的全体同志要在国家质量技术监督局党组的正确领导下，在全国计量战线的同志们的帮助和支持下，高举邓小平理论的伟大旗帜，深入贯彻党的十五大和十五届三中全会精神，继续坚持“以质量为中。，标准化、计量为基础”的。作方针，转变观念、锐意改革、突出重点、坚实基础，全面深化计量工作。让我们共同努力，携手奋斗，以优异…     

信心!决心!决定中国高端印刷机产业未来!

立足现状 探寻未来 在全球印刷市场的三大板块中：美国、欧洲和亚洲,各占全球印刷市场的三分之一,市场总值为6100亿美元,到2011年,全球印刷市场总产值将达7200亿美元。全球印刷产业12强中,10强都是发达国家。但这些国家的印刷市场在2001年以来都发展缓慢,甚至衰退。中国印刷工业总产值在2006年已跃升至世界第三位。2007年印刷总产值4400亿元,较2006年同比增长158％;印刷设备总产值为170亿元,同比增长率为13.3％。     

稳定压倒一切!音质说明一切!

当今专业音响市场上功率放大器品种繁多,但都局限在单一放大功能。ALTO的工程师,针对目前用户以及工程商对于专业音响设备越来越高音质需求和使用要求,以追求完美的扩声音质为诉求,研制开发具有全新概念的功率放大器——MISTRAL系列。MISTRAL系列功率放大器具有不带数字处理功能的CPA系列和带数字音频处理电路的CPD系列,可应对不同需求的用户要求。 MISTRAL CPA系列功率放大器采用全新的     

致谢!

<正>《无机材料学报》2013年的出版工作顺利完成,感谢广大审稿专家对本刊稿件进行了认真审阅,为学报学术水平和质量的提高付出了辛勤的劳动。在此,学报向下列审稿专家的严谨治学和无私奉献表示衷心感谢!     

动起来!

春天来了,天气暖了,别再窝在屋里,拿起相机去拍照吧!下面这些简单的技术与技巧,可以帮助你用数码单反相机凝固下富有戏剧效果的运动画面。和小数码相机相比,数码单反相机在捕捉运动场景时享有得天独厚的优势。我们不可能像顶尖的职业体育摄影师那样在机身和镜头上撒下大把银子,但即便只有一台便宜的入门级数码单反相机和55-250mm、70-300mm这样的低端镜头,我们同样能在各种运动场合大显身手:从机车比赛到马术表演,从拍摄田径比赛到抓拍野生动物。     

致谢!

<正>《无机材料学报》2014年的出版工作顺利完成,感谢广大审稿专家对本刊稿件进行了认真审阅,为学报学术水平和质量的提高付出了辛勤的劳动。在此,学报向下列审稿专家的严谨治学和无私奉献表示衷心感谢!步文博崔晓莉戈磊靳喜海李俊华刘学健孙静王应德叶宁张伟刚曹学强戴世勋龚茂初孔令仁李盛涛刘阳桥陶顺衍王占杰于建国章俞之曾祥斌邓元何岗李驰麟李新军刘志甫王聪温兆银张国军赵东林     

致谢!

正《无机材料学报》2015年的出版工作顺利完成,感谢广大审稿专家对本刊稿件进行了认真审阅,为学报学术水平和质量的提高付出了辛勤的劳动。在此,学报向下列审稿专家的严谨治学和无私奉献表示衷心感谢!     

ISO 13789<建筑物的热性能--传导热损失系数--计算方法>

本国际标准规定了一种方法,可以方便地计算整个建筑物和建筑物局部的传导热损失系数。本标准假定加热空间处于均匀不变的温度。ＩＳＯ13789是有关建筑物和建筑单元热性能的设计和评价计算方法的系列标准之一。计算结果可用于计算年耗能、建筑物的热负荷的输入,也可表示一个建筑物的热传导特性。ＩＳＯ13789国际标准由欧洲标准化委员会(ＣＥＮ)与ＩＳＯ/ＴＣ163热绝缘技术委员会ＳＣ2计算方法分技术委员会共同制定ISO13789《建筑物的热性能——传导热损失系数——计算方法》     

关于死亡的诠释--爱德华·蒙克的<生命之路>

挪威画家爱德华·蒙克由于不幸的生活经历滋生了丰富的悲剧意识和死亡意识,他在自己的作品<生命之路>(组画)中深刻地表现出强烈的死亡意象,融入了他诗意而神秘的情感,他的作品呈现出强烈的震撼力.     

动手实拍!

新生小羊羔是春夏时节最可爱的小生灵之一,我们手把手教您如何用相机拍摄它们娇小美丽的姿态。     

爽哉!数码相机

旅游景点脖子上挂着数码相机的人与日俱增。几年来关于数码相机的报道越来越多,各地摄影器材博览会数码器材部分越来越大,面对当今迅猛发展的科技时代不能不说是广大消费者的一种福气,应当尽力的去享受。我们几个上了年纪的老影友也终于按耐不住数码相机的煽情诱惑,豁出去来个破财寻乐。分别购买了索尼P-50.     

一起来拍照!

跟随我们的实用指导和专业建议,捕捉你眼中出色的特写画面。看了先前的内容,你一定觉得心痒痒的,急切地想拍出自己的特写作品吧。现在,就让我们的实用操作技巧来帮你取得良好的开端。最重要的一点是,成功的特写要求你掌握一些主要的拍摄技术,譬如用最合适最具视觉效果的方法来摆放道具,确保清晰明亮的光线,和对景深的控制。所以说,花时间来思考和不断尝试主体的位置是很值得的,就如同在数码相机的LCD屏或取景器中构图一样。我们已挑选了这些漂亮的化妆品作为拍摄对象,这不仅仅是因为它们色彩鲜艳,更因为它们的形态异常华丽。就怎样把最普通的事物变成出众的相片主角而言,这是个很好的例子。首     

黑白照实拍!

黑白拍摄的初级教程帮助您简单创作出 精彩的黑白影像 回到基础部分往往是帮助我们拍 摄出真正优秀的黑白作品的关 键所在。这里通过为初学者提 供的一些重要技术指导帮您掌握黑白照 的创作。 黑白照片先天的朴素视觉特性决定 了你可以在实际技能的练习中将精力投 入构图与曝光,当然花些额外的时间学 习一下你的图像编辑软件也是非常有帮 助的。 这里我们选择风景作为基础的黑白